Recent advancements in flexible liquid crystal display (LCD) technology have led to improved screen resolution, longevity and higher performance. The technologies related to LCD displays are still emerging and evolving. In contrast to cathode ray tubes (CRTs) that can actively generate light by exciting phosphor molecules, an LCD can receive white light (e.g., from the display background) and filters such white light to produce the various shades of gray and/or colors. To obtain colors, for instance, each pixel can include three sub pixels utilizing lights of various colors (e.g., red, green and blue light) that can be excited and/or energized to emanate respective colors. When the sub pixel is off, the filter can block the specified color of light, in contrast, the open filter allows a desired amount of light and/or color through when the sub-pixel is on. In general, a majority of LCD displays utilize either high ambient light levels or bright backlighting since liquid crystals do not generate light, but rather only block light.
The term “pixel” is actually an abbreviated version of the term “picture element.” Each pixel can display one color and/or one shade of gray. However, since pixels are extremely small, blending often occurs that forms various shades and/or blends of colors and/or grays. The number of colors each pixel represents can be determined by the amount of bits utilized therewith. For example, 8-bit color allows for 2 to the 8th power, or 256 colors to be displayed. At this color depth, “graininess” can occur wherein one color does not appear to blend into another. However, at 16, 24, and 32-bit color depths, the color is well blended, permitting human perception of the screen image.
A critical component of flexible LCD technology is the drive electronics, wherein such circuits energize the LCD and influence such factors as the number of available colors, shades of gray, power consumption, heat generation, video noise, etc. Conventionally, the designs of the commercial parts provide binary or analog output levels. Binary drivers can utilize positive high voltage and electronic ground in operation. In a binary drive scheme for a LCD display panel, rows and columns are driven out-of-phase using waveforms that switch between ground and the high-voltage (HV). An un-driven column is held at approximately zero (0) volts while undriven rows are held at approximate zero (0) volts or are disconnected (allowed to “float”). A fully energized pixel receives an AC voltage with amplitude HV, while a half energized pixel receives an AC voltage with an amplitude of up to HV/2 that is superimposed on a bias voltage. By adjusting the HV amplitude so HV/2 is below the electrooptical threshold of the liquid crystal it will not be activated by this half-amplitude AC, but the DC bias results in excessive power dissipation. Also, a binary driver operating at high voltage can often damage a system because the average DC voltage “seen” by the device can be HV/2, which many devices can not tolerate. If the undriven columns are disconnected (allowed to “float”) the AC voltage received by the half energized pixels would depend on the activation pattern and for worst case pattern be HV which equals the AC voltage for energized pixels. This would result in unwanted activation of pixels.